1. Field of the Invention
The present invention relates to wireless networking, and techniques for organizing, on an ad hoc basis, mobile networks using unmanned devices or vehicles that are movable over a geographic area.
2. Description of the Related Art
Proposals have been made by Internet Engineering Task Force (IETF) groups for improved mobility support of Internet Protocol (IP) based mobile devices (e.g., laptops, IP phones, personal digital assistants, etc.) in an effort to provide continuous Internet Protocol (IP) based connectivity. The IETF has two working groups focusing on mobile networks, a Mobile Ad-hoc Networks (MANET) Working Group that is working to develop standardized MANET routing specification(s) for adoption by the IETF, and NEMO (mobile networks). NEMO uses Mobile IP (MIP) to provide connectivity between mobile networks and the infrastructure (e.g., the Internet). The key component in NEMO is a mobile router that handles MIP on behalf of the mobile networks that it serves.
According to the MANET Working Group, the “mobile ad hoc network” (MANET) is an autonomous system of mobile routers (and associated hosts) connected by wireless links—the union of which form an arbitrary graph. The routers are free to move randomly and organize themselves arbitrarily; thus, the network's wireless topology may change rapidly and unpredictably. Such a network may operate in a standalone fashion, or may be connected to the larger Internet.
A “Mobile IPv6” protocol is disclosed in an Internet Draft by Johnson et al., entitled “Mobility Support in IPv6” and identified by the designation “draft-ietf-mobileip-ipv6-24.txt”, available on the World Wide Web at the IETF website “ietf.org”.
The above-described mobile networking protocols, however, are merely concerned with IP-based connectivity, and rest on the assumption that wireless link establishment and node mobility are uncontrollable factors outside the scope of the mobile networking protocol.
Remote-controlled devices have been used to provide remote sensoring and remote interaction with respect to hostile (e.g., dangerous) environments or locations that are not practical for human intervention. Such remote-controlled devices have included terrestrial robots, aerial drones, satellites, marine or submersible drones, and unmanned spacecraft. Typically these remote-controlled devices have relied on a wireless link with a control station that provides direct control over the operations of the remote-controlled devices; as the remote-controlled devices obtain additional processing power and memory storage capabilities, the degree of real-time controller intervention via the control station is reduced. Still, at some point the remote-controlled device, upon lacking sufficient information to execute an operation, will reach a state where it enters a standby mode while awaiting further instructions from the control station.
Of particular interest is the ability to organize mobile elements within a pervasive network. The term “pervasive network” refers to a network where every thing, device, and user can be continually connected to a common network fabric. Use of a pervasive network would be particularly beneficial in military or rescue operations, where a system (e.g., a mobile network of robotically-controlled mobile nodes) can be quickly deployed (in a manner of hours) without the necessary of manual configuration of each and every mobile node.
Efforts in attempting to implement and deploy a pervasive network have uncovered numerous problems. Attempts for rapid deployment in a given area may encounter operational difficulties if the area of deployment cannot support continuous coverage of each individual mobile node. In addition, changes in topology and the location of the coverage may change at a rapid and unpredictable pace, risking signal loss between various mobile nodes.
One attempt to minimize signal loss is to combine satellite communications (offering wide area coverage) and mobile communications. Use of satellite communications, however, has its own associated problems: satellites are expensive, fragile, and have a limited bandwidth and a limited time interval of line-of-sight availability in the case of satellites that do not have a geostationary orbit. Further, the required power for a mobile base station to transmit to and from a satellite can be both cost prohibitive and dangerous, since the signal transmission can be detected by hostile forces. In addition, there is no established protocol for coordinating land-based mobile nodes and satellites with respect to network management and communications support. Further, military and or rescue operations may need to adopt an inefficient organizational structure in order to accommodate the communications topology inherent in the wireless network.
Still in other systems, such as APCO16 and APCO25 systems (promulgated by the Association for Public-Safety Communications Officials) that service the public safety networks (police, fire and ambulance), wireless technologies are typically deployed using fixed nodes, namely towers and repeaters stationed over a given area of coverage in a logical fashion to provide robust communications during normal and “planned” conditions. However, during catastrophic or unplanned situations (such as a terrorist attack) those fixed node-based systems may not be able to provide adequate coverage to support rescue or police operations.
One technology that has been deployed to support ad hoc rescue operations is a “vehicular” repeater. This allows a vehicle, for example a police car, to act as a repeater for the network. The officer drives his vehicle to a certain area and the vehicle has a “higher power” repeater in it. The officer and others can then use their lower power portable radios to communicate through the repeater within the vehicle thereby extending their range.
This vehicular repeater, however, has several limitations. First, the vehicle must be driven to a specific point by a human driver and that point might not be reachable or might not be a place where the driver needs (or wants) to go. Second, the vehicle only acts as a repeater back to the fixed infrastructure and cannot support local communications. Third, the repeater has limited bandwidth. Fourth, the repeater cannot account for portable devices having varying power requirements.
Yet another common capability is the ability of public safety and military portable radios to enter “talk around mode”. In talk around mode, one or more users choose to communicate point to multi-point with a specific group of users. This is a manual process and requires a decision on the part of the users to enter talk around mode. Additionally, while in talk around mode, the user is typically disconnected from wide area communications. Finally, there is no means to enable members of the “group” to transition from a local communications (akin to wireless LAN) to distant communications (akin to wireless WAN) in situations that may occur as members move positions, as may happen on a battle field or during a emergency situation.